In my country Kenya (that's spelt A-F-R-I-C-A for all you americans reading this). We have a service called M-PESA that allows for such functionality - you can basically pay anyone (person or business) that has an M-PESA account. Heck, you can even withdraw money from an ATM using just your cellphone. It goes without saying that all this is done without fancy 3g phones. look here: http://www.vodafone.com/start/media_relations/news/group_press_releases/2007/safaricom_and_vodafone.html

and still on topic. Well done Slashdotters!